ATC code H05

== ATC Code H05: Calcium Homeostasis Agents ==

The Anatomical Therapeutic Chemical (ATC) Classification System is a system used for the classification of drugs and other medical products. The ATC code H05 is designated for agents that affect calcium homeostasis, which is crucial for maintaining various physiological processes in the human body.

Overview

Calcium homeostasis is the regulation of calcium ion concentration in the extracellular fluid. This process is vital for many bodily functions, including bone formation, blood coagulation, muscle contraction, and nerve function. The ATC code H05 encompasses drugs that are used to manage disorders related to calcium metabolism.

Subgroups

The ATC code H05 is divided into the following subgroups:

• H05A: Parathyroid Hormones and Analogues
• H05B: Anti-parathyroid Agents

Each subgroup contains specific agents that are used to either supplement or inhibit the action of parathyroid hormone (PTH) and related pathways.

H05A: Parathyroid Hormones and Analogues

Parathyroid hormones and their analogues are used primarily in the treatment of conditions such as hypoparathyroidism and osteoporosis. These agents help to increase serum calcium levels by stimulating osteoclast activity, increasing renal tubular reabsorption of calcium, and enhancing intestinal absorption of calcium.

• Teriparatide (H05AA02): A recombinant form of parathyroid hormone used in the treatment of osteoporosis. It stimulates new bone formation by increasing the number and activity of osteoblasts.

• Parathyroid hormone (H05AA01): Used in the management of hypoparathyroidism to maintain calcium and phosphate balance.

H05B: Anti-parathyroid Agents

Anti-parathyroid agents are used to manage conditions characterized by excessive parathyroid hormone activity, such as hyperparathyroidism. These agents work by reducing the secretion or action of parathyroid hormone.

• Cinacalcet (H05BX01): A calcimimetic agent that increases the sensitivity of the calcium-sensing receptors on the parathyroid gland, thereby reducing PTH secretion. It is used in the treatment of secondary hyperparathyroidism in patients with chronic kidney disease and in the management of parathyroid carcinoma.

Clinical Applications

The agents classified under ATC code H05 are used in various clinical scenarios:

• Hypoparathyroidism: Characterized by low levels of parathyroid hormone, leading to hypocalcemia. Parathyroid hormone analogues are used to manage this condition.

• Osteoporosis: A condition of weakened bones, often treated with teriparatide to stimulate bone formation.

• Hyperparathyroidism: Excessive secretion of parathyroid hormone, often managed with cinacalcet to reduce PTH levels and control hypercalcemia.

Conclusion

ATC code H05 encompasses a range of pharmacological agents that play a critical role in the management of calcium homeostasis disorders. Understanding the mechanisms and clinical applications of these agents is essential for healthcare professionals in providing effective treatment for conditions related to calcium metabolism.

References

• World Health Organization. (2023). ATC/DDD Index 2023. Retrieved from [WHO Collaborating Centre for Drug Statistics Methodology](https://www.whocc.no/atc_ddd_index/)
• National Institutes of Health. (2023). Calcium and Bone Disorders. Retrieved from [NIH Osteoporosis and Related Bone Diseases National Resource Center](https://www.bones.nih.gov/health-info/bone)